| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2023-52831: cpu/hotplug: Don't offline the last non-isolated CPU |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| cpu/hotplug: Don't offline the last non-isolated CPU |
| |
| If a system has isolated CPUs via the "isolcpus=" command line parameter, |
| then an attempt to offline the last housekeeping CPU will result in a |
| WARN_ON() when rebuilding the scheduler domains and a subsequent panic due |
| to and unhandled empty CPU mas in partition_sched_domains_locked(). |
| |
| cpuset_hotplug_workfn() |
| rebuild_sched_domains_locked() |
| ndoms = generate_sched_domains(&doms, &attr); |
| cpumask_and(doms[0], top_cpuset.effective_cpus, housekeeping_cpumask(HK_FLAG_DOMAIN)); |
| |
| Thus results in an empty CPU mask which triggers the warning and then the |
| subsequent crash: |
| |
| WARNING: CPU: 4 PID: 80 at kernel/sched/topology.c:2366 build_sched_domains+0x120c/0x1408 |
| Call trace: |
| build_sched_domains+0x120c/0x1408 |
| partition_sched_domains_locked+0x234/0x880 |
| rebuild_sched_domains_locked+0x37c/0x798 |
| rebuild_sched_domains+0x30/0x58 |
| cpuset_hotplug_workfn+0x2a8/0x930 |
| |
| Unable to handle kernel paging request at virtual address fffe80027ab37080 |
| partition_sched_domains_locked+0x318/0x880 |
| rebuild_sched_domains_locked+0x37c/0x798 |
| |
| Aside of the resulting crash, it does not make any sense to offline the last |
| last housekeeping CPU. |
| |
| Prevent this by masking out the non-housekeeping CPUs when selecting a |
| target CPU for initiating the CPU unplug operation via the work queue. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52831 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 6.1.64 with commit 3410b702354702b500bde10e3cc1f9db8731d908 |
| Fixed in 6.5.13 with commit 335a47ed71e332c82339d1aec0c7f6caccfcda13 |
| Fixed in 6.6.3 with commit 3073f6df783d9d75f7f69f73e16c7ef85d6cfb63 |
| Fixed in 6.7 with commit 38685e2a0476127db766f81b1c06019ddc4c9ffa |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2023-52831 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| kernel/cpu.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/3410b702354702b500bde10e3cc1f9db8731d908 |
| https://git.kernel.org/stable/c/335a47ed71e332c82339d1aec0c7f6caccfcda13 |
| https://git.kernel.org/stable/c/3073f6df783d9d75f7f69f73e16c7ef85d6cfb63 |
| https://git.kernel.org/stable/c/38685e2a0476127db766f81b1c06019ddc4c9ffa |
